When a ship has suffered a breach in its hull, the most urgent requirement is to stop or reduce the amount of inrushing water so the danger of immediate sinking can be prevented. A breach in a hull with a total area of 12 square inches, located 10 feet below the water line, allows water to enter the ship at a rate of nearly 9,000 gallons per minute (GPM). At such a rate most ships will quickly fill with water and sink.
Present techniques for plugging relatively small holes (i.e., up to six inches) require ship's personnel to pound precut pieces of wood into the hole. Of course, this procedure has a number of drawbacks. For example, if the compartment has already filled with a large amount of water such that the hole is underwater, it can be extremely difficult to swing a hammer to pound the wooden blocks into the hole. In addition, it is often difficult to keep the blocks in the hole where water is rushing in through the hole, since, apart from the wood swelling, there is nothing to hold the blocks in the hole. If the hole is part of a tear in the steel, fiberglass or wooden hull of a ship, pounding in a plug can make the tear larger. Further, as the wooden block swells it can force the tear apart and make it bigger.
If the total size of the hole can at least be reduced to an equivalent of 1 square inch at the same 10 feet depth, the amount of water entering the ship could be reduced to less than 64 GPM. A rate of 64 GPM flooding can be controlled using pumps. The extra time gained by this reduced influx of water can mean the difference between losing and saving the ship.
Since the water that will be flooding into the ship is under pressure it will wash away anything not properly supported or strong enough to withstand this pressure. Thus, any device used to stop the flooding must be quick and easy to use, and must be strong enough to survive the inrushing water.
The disclosed device can be ready to use as soon as its guide arms are opened and the device is pushed into the hole and the trigger is activated. The inrushing water helps open the device, and once the device is fully opened and covering the breach from outside the hull, the guide arms are ratcheted down toward the inside of the hull to hold the device against the hull.